Tubular blade for electrical plug caps



Sept. 30, 1969 F. KLUMPP, JR

TUBULAR BLADE FOR ELECTRICAL PLUG CAPS 2 Sheets-Sheet 1 Filed May 22,1967 l I I I I l m I N s.

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TUBULAR BLADE FOR ELECTRICAL PLUG CAPS Filed May 22, 1967 2 Sheets-Sheet2 INVENTOR. 45 I FERDINAND A? an, J/P.

v rZn'nf'qk United States Patent US. Cl. 339276 1 Claim ABSTRACT OF THEDISCLOSURE A continuous blade strip which can be wound into rollscomprising a plurality of sets of generally round tubular bladespositioned between a pair of generally flat blades, the blades beingformed of oppositely positioned folded over and contacting portions, oneof the portions of each blade having an extension forming a terminal forengaging a conductor, the oppositely disposed contacting portionsproviding the tubular blade having therein elongated trough-likeembossed portions, the embossed portions forming an elongated tubularblade closed at its ends; also a tubular blade per se as describedabove; also a method for forming the strip and the tubular blade per se.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to blades for use in electrical cap plugs and particularly toblade strips useful in pro viding the three blades used in electricalcap plugs in which one of the blades is usually grounded. It alsorelates to the grounding blade itself of tubular construction. It alsorelates to the method of making the strip and the grounding blade.

Description of the prior art In the prior art, plugs primarily for powertools are available having two, usually, fiat blades for fitting intothe conventional or other sockets, and a grounding blade or pin, usuallyround, and offset from the other two terminals in the plug.

Each of the above blades is usually provided with a solder type orsolderless type (crimped) terminal for receiving the wires or conductorsof the cord or cable, one of which is the ground wire.

There are several disadvantages in the use of the old type of groundblade. Normally it was formed separately from the fiat blades from aseparate strip of metal, usually brass, supplied in rolls. The generaltechnique used was that described in my Patent 2,558,052. However, afterbeing stamped from the strip, it was rolled to form a round tubularterminal which could be received by the socket. This meant handling twoseparate rolls and performing two separate operataions on two separatepress machines when forming the blades usually requiring two operations.It also meant handling the blades and cords in two separate operationsat two separate stations to connect the blades to the conductors by theassemblers. All three blades could not be connected at one time.

Furthermore, in molding the cap around the blades, the round tubularblades had to be threaded through a very accurately formed roundaperture in the loading bar and its complementary clamp prior tomolding, another time consuming operatioin. The conventional round pinavailable made it impossible to use the usual slot arrangement in theloading bar which could receive the flat blades.

To form the conventional round tubular blade, it was also necessary touse wider punched out sections in the Patented Sept. 30, 1969 "ice stripthan for the flat blade and then form the punched out sections around amandrel. Thus, more material was required to make the round blade thanthe flat blade.

It was also necessary to punch a tongue in the terminal end of the roundblades and fold it transversely of the open end of the blade to closethe blade so as to prevent the molding material from entering the insideof the pin during molding operations. This construction weakens the pinof its terminal end.

SUMMARY OF THE INVENTION The tubular blade comprises folded overcontacting portions, the contacting registering portions of the tubularblade including oppositely disposed elongated embossed trough likesections of preferably semicircular cross section forming a tubularblade closed at its ends, one of the portions of the blade having anextension providing a terminal for engaging the conductors of a cord,and the other portion terminating in a stop.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a plan view of the plugcap blades in different stages of the process of manufacture,

FIGURE 2 is an end view of FIGURE 1,

FIGURE 3 is a perspective with the cap' shown in perspective showing therelationship of the blades in a finished product,

FIGURE 4 is a side elevation of the tubular blade in finished form,

FIGURE 5 is a top view of FIGURE 4,

FIGURE 6 is a perspective of the tubular blade,

FIGURE 7 is a top view of the cap and blade assembly,

FIGURE 8 is a side elevation of FIGURE 7, and

FIGURE 9 is a partial view of the loading bar used in the moldingoperations.

DETAILED DESCRIPTION Referring to the drawings, FIGURE 1 shows a strip10 of suitable material, such as brass, of a width suitable for formingthe blades from the material. As the strip 10 is passed through a press,various operations take place from punching apertures to forming theblades.

In the first step rows of holes or apertures 11, 12, 13 and 14 arepunched out as well as the blanks 15. At a later stage, when the strip10 has progressed far enough, the compound punch and die severs thestrip along the lines 16, 17 leaving a small lug connection portion 18which can later be easily broken.

At a later position the blades including the tubular blade 20 and flatblades 21 are formed by dies and folded in part. The final folding stepsprovide the formed tubular blade slightly separated from the two flatblades as shown at the end of the strip. During these later stages theterminals 22 are formed.

As shown in FIGURES 3, 7 and 8, the round tubular ground blade 20 ispositioned displaced from the flat blades 21, 21 in the cap 25. Theblades are connected to the conductors 27, 28 and 29 of the cable orcord 30.

Referring to FIGURES 4, 5 and 6 the round tubular blade 20 comprises thecomplementary portions 35 and 36, each being of an elongated trough likeshaped closed at the ends. This prevents molding material from enteringthe interior of the tubular portion during molding operations. At theend opposite the fold the blade is provided with the anchoring orlocking element 37 received within the cap. To make it possible to use asimple molding bar, I provide the flat portion 38. The solderlesscrimping terminal 22 is provided on the extension opposite the portionproviding locking element 37.

Referring to FIGURE 9, the clamping bar comprises a lower slottedportion 40 and a cooperating upper memher 41. In assembly an operatortakes a set of blades including blade 20 and two adjacent blades 21 andassembles the harness arrangement including the three conductors 27, 28and 29, this being done in a single operation on a crimping apparatus.The assembled parts are then inserted in the clamping bar 40, 41. Flatportions 38, 42 and 43 are inserted in slots 44, 45 and 46 and clampedbetween the two parts, the bar defining the cap line when placed in themolding machine.

I claim: 1. A round tubular blade for a molded cap, said tubular bladecomprising oppositely (a) disposed troughdike contacting portions, (b)one of said portions including an embossed section of semicircular crosssection and terminating in a stop portion extending outwardly from andperpendicularly of said embossed section and providing a locking elementto be received within a molded cap, (6) the other of said contactingportions having a complementary embossed section of semicircular crosssection in abutting relation with said one por- UNITED STATES PATENTS1,674,246 6/1928 Gaynor et a1 339-196X 2,163,779 6/1939 Draving 339-220X 2,861,324 11/1958 Klumpp 339 218 X 3,134,632 5/1964 Kimball et a1.339-195 3,268,847 8/1966 Klumpp 339-184 X RICHARD E. MOORE, PrimaryExaminer US. Cl. X.R.

